A solid rock suspended in air by a spring scale, has a measured mass of 9.00 kg. when the rock is submerged in water, the scale reads 3.30 kg. What is the sensity of the rock? (water density = 1000 kg/m^3
Answer 1.58X10^3 kg/m^3
2006-11-14 12:51:09 · 5 answers · asked by mastersource2005 5 in Science & Mathematics ➔ Physics
let volume of the rock be v and density be d...
now mass=vd=9.00kg
the weight of rock in water is 3.30kg
i.e.original weight of rock-buyoyancy (float) force of water =3.30
the float on the rock is volume of rock * density of water
vd-v.1000=3.30 (1)
5.70=v.1000
v=5.7*10^-3
hence d-1000=3.30 /(5.7 *10^-3) (from eq 1)
=580
hence d= 1.58*10^13
2006-11-14 13:06:31 · answer #1 · answered by indurti karthik 2 · 1⤊ 0⤋
The density of water is holding up the rock, so the rock's extra weight after being dipped in water allows us to figure out it's density related to the water. The rock displaced 9-3.30 =5.7kg of water. Water has a density of 1000 kg/m^3 so 5.7 kg of water takes up 0.0057 m^3 of space. That means that the rock's volume is also 0.0057 m^3 since that is the amount of water displaced.
Density = Mass/ Volume
Now that we know the mass and volume of the rock, we just plug in the numbers
Density = 9kg / 0.0057 m^3
Density = 1578.9473684211 kg/m^3
or 1.58X10^3 kg/m^3 when put into scientific notation.
2006-11-14 21:24:50 · answer #2 · answered by Roman Soldier 5 · 0⤊ 0⤋
The density of a solid object is its mass divided by its volume. The spring scale in air gives you the rock's mass and the change of weight in water gives you the weight of water displaced allowing you to calculate the volume of the water displaced thus the volume of the rock. You must understand that physical relationship to calculate the density otherwise the answer will not help you pass a test. Good luck.
2006-11-14 21:14:30 · answer #3 · answered by Kes 7 · 0⤊ 0⤋
To find the density of the rock you have the mass of the rock (9 kg) and so you need to find the volume of the rock.
volume of the rock = (mass of water displaced)/(density of water)
volume of the rock = (9.00kg - 3.30kg)/(1000 kg/m^3)
= 0.0057m^3
density of the rock = 9.00 kg/0.0057m^3 = 1.58X10^3 kg/m^3
2006-11-14 21:10:09 · answer #4 · answered by Matisse 2 · 1⤊ 0⤋
darn, all the work's not done for you in the back of the book?
never was for me either. think they would have improved in 20 years.. huh.
2006-11-14 21:00:24 · answer #5 · answered by homelessinorangecounty 3 · 0⤊ 0⤋